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How do I index?

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drizzle

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#1
I am undercutting some transmission gears for a Honda motorcycle. I have a JET JDM18 mill and a Yuasa dividing head. I have an aluminum billet machined to hold the gear and the billet is held in my dividing head. How do I index each of the 5 dogs to the cutter so when I move the table left and right, I am getting a straight cut across the face of the dog? Current issue i have is, I have my dial test indicator held in a collet in the mill but it spins..... its not square to the table so my reading is off. I spend 10 minutes getting the face perfectly indicated in and when I looked down the side of the machine, the face was not parallel with the axis I was going to use to make my cut. I was off like 15 degrees. I am posting some reference pics from google for right now.

(Wont let me attach links to pictures)

If you notice, the dogs are pie shaped. When the gears are engaged, the dogs only mate about halfway down into the pockets so I can indicate down lower to get the most accurate reading. I just cant figure out how to get my indicator squared off of anything to get an accurate reading.
 

drizzle

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http://www.psychobike.com/forums/attachments/suzuki-hayabusa/81841d1325983571-cut-trans-img_2622.jpg
https://ssli.ebayimg.com/images/g/NHgAAOSw-0xYNHPc/s-l1600.jpg
https://www.hayabusa.org/forum/attachments/shifter1stgear-jpg.1537401/
http://img.photobucket.com/albums/v356/Black_Bean/IMG_0338.jpg
https://www.orientexpress.com/images/Product/medium/20447.jpg

for those that dont know, when you shift a transmission with no clutch, it rounds off the corners of the dogs and creates a wedge shape which pushes the gears part under power. To repair this you resurface them to 90 degrees or undercut/back cut them with a dovetail cutter so that they stay locked in and the power load will suck them together, as seen here....
http://kawtriple.com/mraxl/trans_manual/undercut.jpg
 
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Mitch Alsup

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#3
I am undercutting some transmission gears for a Honda motorcycle. I have a JET JDM18 mill and a Yuasa dividing head. I have an aluminum billet machined to hold the gear and the billet is held in my dividing head. How do I index each of the 5 dogs to the cutter so when I move the table left and right, I am getting a straight cut across the face of the dog?
Chuck (or collet) a DI or DTI in the spindle.
Hold gear to be machined in vise or fixture.
Adjust vise/fixture until you can traverse the gear on the table with the DI/DTI not showing any error during the traverse.

That is, the face of the gear gets trammed just like the vise gets trammed.
 

drizzle

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I did that... I put the DTI in the collet BUT IT SPINS, HOW DO I SQUARE IT TO THE TABLE, If the indicator is on any sort of angle that is not 90 or 180 to the table, you get false readings. HOW DO I SQUARE IT?
 

JimDawson

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#5
As long as the indicator is more or less aligned to the axis you should be able to dial in the part to the desired travel axis. I normally put the head in back gear to keep the spindle from rotating. Normally there shouldn't be enough force on the indicator to even overcome the friction of the spindle. I guess it depends on what type of indicator you're using and how far the stylus is off of the spindle centerline. Normally I use a DTI for setups like this.


 

drizzle

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#6
I am using a DTI, there is resistance on the head but its belt drive so I cant keep change speeds, There is 2 bolts and an idler pulley that needs to be loosened with sockets/wrenches to change the belts. PITA. so doing the best I can do square it and leave it will work? I guess I can try that.
 

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#7
Can you post a picture of your setup? Using a DTI can not put enough force on the spindle to rotate it in any normal configuration, everything should be pretty close to the spindle centerline. I'm a little confused here. o_O
 

drizzle

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#9
also, I have no intentions of figuring out the math on the dividing head for this, I just want to indicate each face of the dog and cut it. I plan to use marker or dye on the faces and mesh with the corresponding gear to check for high spots and I will fine tune from there. I dont think that aspect of this has to be perfect, but cutting them even and retaining the pie shape of each dog is more critical. open to opinions.
 

drizzle

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also, I used the marker as a referrence. its pretty much parallel with the table to show what I am trying to index/indicate in. i change the position of the gear in each picture.
 

JimDawson

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#11
Messy? You should see my shop :)

Looks like your setup is OK. I would have the stylus more vertical, but what you show should work, I can't imagine being able to put enough torque on the spindle to rotate it with that setup.

So the process is to make contact with the part, move the x axis to check the alignment, rotate the rotary table a bit, check again, rinse-repeat until the work surface is aligned with the x axis (zero movement on the DTI dial)
 

P. Waller

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#12
The math is simple, 72 Deg.
 

drizzle

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#13
so once I indicate 1 face, 72 degrees will line me up perfect and I wont have to indicate the other faces or should I still check? So, I should set the head to 0 first obviously......
 

P. Waller

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#14
Yes. 5 divisions of a circle, 360/5 = 72
However do not expect OEM parts to be as accurate as you think they are or should be, it is likely that the OEM finished surfaces are far harder then you anticipate as well.
 

drizzle

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#15
I know its probably not super accurate but I want to stay close. Yes, its a hardened gear and looks like it was probably shot peened aswell. I have the appropriate cutter for it. carbide with ATLIN coating? and going to take light passes at 2700-3000RPM as people have suggested. Its a small bit... 1/4"? with 3/8" shank.
 

P. Waller

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#16
Good luck with the machine pictured using carbide tooling.
If you do not mind my asking what does a new OEM gear cost?
 

Mitch Alsup

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#17
Instead of indicating on the wall of the gear, indicate on the teeth--these are the only real reference surfaces you have.

Face of a tooth--vertically.
 

drizzle

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#18
Instead of indicating on the wall of the gear, indicate on the teeth--these are the only real reference surfaces you have.

Face of a tooth--vertically.
what is that going to do when i am making a horizontal cut? I am cutting those 5 dogs in the center of the gear, they are not lined up with any one tooth.
 

drizzle

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#19
Good luck with the machine pictured using carbide tooling.
If you do not mind my asking what does a new OEM gear cost?
i have talked to alot of machinist that have used these mills, they are not bad...... obviously not making satellite parts with it but for what im doing it should be fine. new gear is about $70...... but they are discontinued and that still doesnt prevent future issues. To have this done by a shop that does this as a standard service is about $500. If I fail at it, oh well... atleast I tried.
 

drizzle

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#20
I reindicated the gear. looks good but cant cut because my 3/8 collet appears to be stripped and I cant re-tap it. tried but no way to hold the collet without damaging it and its so tight that I may end up busting a tap in it. will order a new one. any suggestions on where to get one? Im always hesitant of ebay china crap. maybe I get lucky and find a Bridgeport collet.
 

P. Waller

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#21
Have at it then.
There is a reason that others charge $500.00 to modify a $70.00 part, you will soon find it I suspect.
 

drizzle

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#22
looking on MSC, how do I choose a collet? 0.0011 TIR or 0.0007 TIR? I need a 3/8 R8 with 7/16-20 thread.
 

P. Waller

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#23
I reindicated the gear. looks good but cant cut because my 3/8 collet appears to be stripped and I cant re-tap it. tried but no way to hold the collet without damaging it and its so tight that I may end up busting a tap in it. will order a new one. any suggestions on where to get one? Im always hesitant of ebay china crap. maybe I get lucky and find a Bridgeport collet.
If you are going to use carbide end mills in an R8 spindle machine buy the most concentric collets that you are willing to pay for, Lyndex is an excellent mid priced tool.
 

drizzle

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#24
Have at it then.
There is a reason that others charge $500.00 to modify a $70.00 part, you will soon find it I suspect.
they are doing more than 1 gear for that price. Its like $110 for 1 gear.
 

drizzle

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#25
If you are going to use carbide end mills in an R8 spindle machine buy the most concentric collets that you are willing to pay for, Lyndex is an excellent mid priced tool.
post a link where to get....
 

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#26
looking on MSC, how do I choose a collet? 0.0011 TIR or 0.0007 TIR? I need a 3/8 R8 with 7/16-20 thread.
All R8 collets have the same thread.
The TIR only applies to the collet itself in a test fixture during manufacturing, this does not mean it will hold these numbers when you put it in your machine of unknown run out.
 

P. Waller

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#28
Stop with the cheap.

You want to do a machining operation.
Either this is a commercial venture and you want to do it for less than others.
Or it is a personal project where cost is secondary.

Either way purchase what is required and have at it win or lose.
 

drizzle

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#29
I'm cheap when it comes to opening my wallet, if I can find a deal, that allows me to invest MORE into tooling, fixtures...etc yada yada.... I'm not cheap with quality. I waited and found myself the Yuasa dividing head because I didnt want to spent $2000 on a new one and wasnt going to buy the ebay special for $200. It adds up. just trying to be thrifty.
 
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